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First Page

63

Last Page

76

Abstract

Qualitative and quantitative data are presented for secondary xylem of 14 species of four genera of Calyceraceae; root wood is studied for acaulescent perennials and one annual. The wood anatomy of most species of Calycera has character states identical to those seen in wood of most Asteraceae (including phylads of Asteraceae thought to be basic in that family). Goodeniaceae have two features (tracheids, diffuse parenchyma) more primitive than corresponding conditions in Asteraceae and CaIyceraceae according to traditional criteria. Diversity in wood anatomy within Calyceraceae is explainable in terms of adaptation to particular ecological conditions. Although woods of the family as a whole are xeromorphic, most Calycera species show few adaptations to extreme xeromorphy. The highest degree of wood xeromorphy occurs in species of relatively high elevation or high latitude. The presence of pseudoscalariform pitting, with transitions to helical-banded secondary xylem vessels, very much like those of primary xylem, in Boopis graminea and Nastanthus spp., coupled with absence of Iibriform fibers (replaced by axial parenchyma) are probably related to expansion and contraction of the wood in response to fluctuation in moisture availability.